There are many, many variations of this joke.
One day a little boy and a little girl are playing basketball and the boy is losing to the girl. Feeling a bit put out he digs into his pocket and pulls out three marbles and says “I’m better then you because I have three marbles.”
The girl promptly pulls out five jacks and says “Well I’m better still because I have five jacks and five jacks are better then three marbles!”
The boy frowns and digs into his pocket and pulls out two quarters and says “I’m better then you because I have fifty cents.”
The girl pulls out six dimes and says “Well I’m better still because I have sixty cents and sixty cents is better then fifty cents.”
Again the boy frowns, thinks for a moment and then smiles. He pulls down his pants and whips out his penis and says “Well I’m better then you because I have one of these and I know you don’t have one of these!”
The little girl thinks and then lifts up her dress and says “Well I’m better still because I have a vagina and with one of these mommy says I can get as many of those as I want!”
Many a true word…